Fire tube boiler



March 22, 1966 E, T, BLQCKLEY ETAL 3,241,529

FIRE TUBE BOILER 2 Sheets-Sheet l Filed June 50, 3.964

March 22, 1966 E, T BLOCKLEY ETAL 3,241,529

FIRE TUBE BOILER 2 Sheets-Sheet 2 Filed June 30, 1964 N www 0L MKM C MOG NLA IBM T.E. ET mT wm E EVN United States Patent C) 3,24] 529 FIRE TUBE BOILER Eugene T. Blockley, Chattanooga, and Everett E. Magnuson, Signal Mountain, Tenn., assignors to Eclipse Fuel Engineering Co., Rockford, lll., a corporation of Illinois Filed .lune 30, 1964, Ser. No. 379,281 9 Claims. (Cl. 122-409) This application is a continuation-impart of our copending but now abandoned United States patent application Serial No. 229,847, tiled on October 1l, 1962 and entitled Firetube Boiler.

The present invention relates generally to horizontal fire tube boilers and has particular reference to a novel tire tube boiler which, when employed for liquid phase heating, presents numerous advantages over conventional liquid phase tire tube boilers which are widely used in industry for both liquid phase and vapor phase heating.

Present-day tire tube boilers are possessed of several limit-ations, principal among which is uneven heat distribution and consequent uneven tube elongation which causes irregular buckling of the tube sheets which support the ends of the various tire tubes. This bucklingof the tube sheets frequently results in the creation of cracks in the tube sheets. Furthermore, uneven elongation of the tire tubes has a tendency to destroy the seals at the ends of the tubes where they are either welded or rolled into contact or sealed relation with the tube sheets. These limitations are particularly prevalent in connection with fire tube boilers which have liquid phase heating systems employing a transfer medium such, for example, as water.

Another limitation that is attendant upon horizontal fire tube boilers when used for liquid phase heating, resides in localized thermal shock to one or more of the ire tubes when the cold liquid is introduced into the Water or other liquid phase of the system at -a selected localized region thereof. This causes rapid shrinking of the involved tube or tubes and consequent rupture at the tube ends as heretofore described.

Another type ofre tube boiler which is employed for liquid phase heating and has horizontally disposed tire tubes attempts to secure a more even distribution of heat throughout the liquid phase of the system by providing baffles at longitudinally spaced regions within the boiler shell, these baffles serving to direct the liquid in a generally serpentine path across the tubes transversely thereof from one end of the boiler to the other. This necessitates the threading of the tubes longitudinally through a large number of aligned holes in the baille plates and tube sheets at the time of boiler construction or tube replacement and materially increases the cost of the boiler as a whole.

The present invention is designed to overcome the aforementioned limitations that are attendant upon the `construction and use of horizontal tire tube boilers and, toward this end, it contemplates the provision of `a fire tube boiler having re tubes which extend horizontally and communicate with a common combustion chamber at one end of the boiler shell and with a ue gas collector at the other end of the shell, the Water phase of the system being devoid of batiies or other intermediate tube supports, and there being novel liquid circulation and distribution means whereby the liquid is evenly distributed throughout the liquid phase of the system from its `region of introduction to its region of discharge to the end that none of the re tubes will encounter cold spots nor will the tubes be subjected to undue uneven heating in localized regions thereof and, consequently, no one tube or group of tubes will be subjected to greater -bustion phase.

Patented Mar. 22, 1966 ICC heat and resultant thermal expansion than the other tubes.

Another object of the invention is the provision of a horizontal tire tube boiler wherein the liquid distribution system is so designed that, although the flow of liquid is generally transversely across the horizontally disposed fire tubes, a gradual component of longitudinal liquid flow takes place and, as a result, the colder liquid flows in slightly greater volume at the `hot end of the boiler near the combustion chamber into contact with the lire tubes than it does at the colder end of the boiler where some -of the heat within the tubes has been dissipated, thereby further contributing toward greater heat-transfer efficiency and heat stabilization throughout the liquid phase of the system.

The provision of a boiler which is of relatively simple design so that it is capable of ease of assembly or dismantlernent for purposes of inspection and tube replacement; one which may be manufactured at an initial low cost; one which is so constructed that all of the horizontal re tubes receive heat from the combustion chamber in equal amounts; one in which such thermal elongation as necessarily takes place in connection with the fire tubes will take'place in equal amounts so that such tube sheet displacement as may occur will be in the form of a gradual outward bulging well within the ability of the individual seals at the tube ends to withstand it; and one in which back pressure within the combustion space is minimized, are further desirable features which have been borne in mind in the production and development of the present invention.

Other objects and advantages of the invention, not at this time enumerated, will become readily apparent from `a consideration of the following detailed description.

In the accompanying two sheets of drawings forming a part of this specification, one illustrative embodiment of the invention has been shown.

In` these drawings:

FIG. 1 is a View, partly in central longitudinal vertical and partly in elevation, of a horizontal re tube boiler constructed in accordance with the principles of the present invention;

FIG. 2 is a sectional view taken on the line 2-2 of FIG. 1;

FIG. 3 is an enlarged bottom plan View of one of two distribution manifolds which are employed in connection with the invention;

FIG. 4 is an end View of the distribution manifold which is shown in FIG. 3, certain parts being broken away and other parts being shown in section for clarity of illustration; and

FIG. 5 is an opposite end view of the distribution manifold.

Referring now to the drawings in detail and in particular to FIG. 1, the boiler which is illustrated therein is designated by the reference numeral 10 and hasbeen schematically portrayed for a better understanding of the ilow of liquid through the liquid phase of the system and of the tlow of combustion gases through the com- The details of the boiler shell, such as any insulation which may be associated therewith, the mechanical connection between the various sections thereof, the combustion chamber, the burner and its mountings, the control devices, and other boiler instrumentalities which may be employed and may vary widely in their construction and design, have been omitted from the disclosure of the drawings since ,the relation which they bear to the present invention is only incidental.

The boiler 10 is essentially a liquid phase boiler and is designed for rising the temperature of liquids, such as water, certain, types of Dowthern and other proprietary heat transfer liquids, and certain heat transfer oils. Briey, the boiler comprises an elongated horizontally disposed boiler shell 12 of generally cylindrical design, a combustion chamber 14 at the front end of the boiler, and a flue gas collector 16 at the rear end of the boiler. The open ends of the shell 12 are closed by front and rear tube sheets 18 and Ztl, the front sheet 18 separating the interior of the shell from the combustion chamber and the rear sheet 20 separating the interior of the shell from the tlue gas collector.

The combustion chamber 14 is generally of cylindrical design and includes a cylindrical side wall 22 and a circular front wall 38. The tube sheet 18, in effect, con stitutes the front wall of the boiler shell. The walls 22 and 30 are preferably refractory lined as indicated at 32.

A burner mounting is schematically illustrated at 34 and carries a burner assembly including a burner nozzle 35 which projects through the wall 22 in the usual manner of burner installation and directs the gaseous or liquid constituents of combustion into the combustion space 36 of the chamber 14. The burner mounting and burner assembly are preferably mounted on the wall 22 at a region which is remote from the tube sheet 18 so that the combustible constituents are introduced into the combustion space near the front wall 30 to allow for turbulence of the ignited gases before entry thereof into the various fire tubes which are associated with the shell 12.

The two tube sheets 18 and 20 are similar in their design and construction and, therefore, only one of them, namely, the front tube sheet 18, has been disclosed in the drawing in plan elevation (see FIG. 2). Each tube sheet is in the form of a circular plate which has a flanged rim 40 for attachment to the adjacent end of the shell 10 and is provided with a series of holes 42 for reception therein of the adjacent ends of a group or series of horizontally disposed tire tubes 44. The ends of the fire tubes 44 may be secured in the holes 42 by any suitable process as, for example, by welding or, as illustrated herein, by expanding and rolling the tube ends over the rims of the holes. The holes 42 are disposed in a generally circular pattern so that there is a generally equal distribution of fire tubes and equal spacing between adjacent parallel re tubes in the group thereof. Near the bottom of each tube sheet and near the top thereof, there is an absence of holes 42 in order to accommodate a sealed handhole 46 and the placement of certain liquid distribution manifolds within the liquid phase of the boiler as will be made clear presently.

The flue gas collector 16 is of generally cylindrical design and embodies a cylindrical side wall 50 and a circular rear wall 58. The tube sheet 20, in effect, constitutes the front wall of the flue gas collector 16. A stack 60 for the products of combustion extends upwardly from the top portion of the side wall 50. The flue gas collector 16 communicates with the combustion chamber 14 through the various fire tubes 44 as is conventional in connection with a horizontal re tube boiler.

As best shown in FIG. 1, the generally cylindrical boiler shell 12 is provided with a liquid inlet 62 adjacent to the bottom thereof and in close proximity to the front tube sheet 18. The shell 12 also is provided with a liquid outlet 64 adjacent to the top thereof and in close -proximity to the rear tube sheet 20. The boiler 10 of the present invention is essentially a forced feed liquid phase boiler and, in order to induce proper ilow of liquid through the shell 12 and across the various re tubes 44, the inlet 62 is operatively connected to a source of liquid under pressure, for example, pressure which is induced by the provision of a suitable pump 66 in the liquid inlet line. Ordinarily, the disposition of the inlet and outlet as heretofore described would call for a generally diagonal flow of the liquid undergoing heating across the shell with considerable short-circuiting of the liquid through the medial regions of the shell. However, according to the present invention, and in order to prevent such short-circuiting and to effect a more even distribution of the heat transfer effect within the shell, an elongated liquid inlet distribution manifold 70 is disposed within the shell 12 and in the lower regions thereof, and a similar liquid outlet collection manifold 72 is disposed within the shell in the upper regions thereof. The two manifolds 70 and 72 are similar in their design and construction but they assume opposite or inverted relation ships within the boiler shell.

As shown in FIGS. l, 3 and 4, the liquid inlet distribution manifold 70 is of inverted trough-like design and comprises an elongated manifold side wall 74 and front and rear semi-circular end walls 76 and 78, respectively. The wall 74 is generally semi-circular in transverse cross section and embodies two longitudinally extending parallel rows of holes 88 therein, the rows being approximately spaced 30 apart on the curved surface of the wall and being equally spaced from a medial longitudinal and radial plane of the wall. The specific number of holes involved is not critical and depends upon such variable factors as boiler capacity, the character of the liquid undergoing heating, especially its viscosity at given temperatures, and mechanical boiler design features. Irrespective, however, of the number of holes employed, the essential features of the invention are not disturbed. The end wall 78 is imperforate while the end wall 76 is provided with two spaced holes 82 therein. By employing two series or rows of holes and positioning the rows as particularly heretofore described, the liquid which enters the shell interior ows upwards and outwards in divergent streams and, consequently, is so diffused that optimum heat transfer is obtained and the fire tubes are subjected to a minimum amount of shock. The particular angle at which the two rows of holes are positioned apart is highly critical.

The liquid outlet collection manifold 72 is similar to the distribution manifold 70, differing therefrom only by the provision of slightly larger diameter holes in the walls thereof. The distribution manifold includes an upright trough-like manifold side wall 84 and front and rear semi-circular end walls 86 and 88. Holes 90 are formed in the wall 84 and are preferably placed in a manner similar to the placement of the holes 80 in the wall 74 of the manifold 70. The front end wall 86 may be provided with a pair of holes 92 therein and they are positioned similarly to the holes 82 in the end wall 76 of the manifold 70.

The rectangular rims of the two manifolds 70 and 72 are secured in a sealed manner, as by welding, to the inner surface of the shell 12, the manifold 70 being inverted and encompassing the liquid inlet 62 and the manifold 72 encompassing the liquid outlet 64. The longitudinal extent of both manifolds 70 and 72 is only slightly less than the distance between the two tube sheets 18 and 20. Thus, the manifold 70 encompasses the liquid inlet 62 near the extreme forward end region of the manifold 70, while the manifold 72 encompasses the liquid outlet 64 near the extreme rear end region of the manifold 72. The end wall 76 of the manifold 70 directly opposes one peripheral region of the tube sheet 18 while the end wall 86 of the manifold 72 directly opposes the opposite peripheral region of the tube sheet.

In the operation of the boiler 10, due to the relatively large combustion space afforded within the combustion chamber 14, very little back pressure is generated so that relatively smooth burner operation may be expected. Furthermore, due to the remoteness of the burner mounting 34 from the tube sheet 18, excess heat at the entrance to the various lire tubes 44 is prevented and the amount of heat supplied to all of the tire tubes is substantially equalized. The relatively cold liquid which passes into the shell 12 through the liquid inlet 62 under the inuence of the pump 66 distributes itself, so to speak, withv in the distribution manifold 70 and ows generally rearltively cold liquid generally upwardly and outwardly with asecantial component of motion into the interior of the cylindrical shell 12 so that this liquid is widely distributed within the shell from the bottom regions thereof.

, Due to the slightly higher pressure of liquid at the inlet yend of the manifold 70, the volume of liquid leaving ,the manifold through' the forwardly disposed holes 8i) is slightly greater than the volume of water leaving the `rearwardly disposed holes, the pressure differential decreasing as the holes `progress rearwardly. Thus, al-

, though short-circuiting of the liquid diagonally across the shell from the liquid inlet 62 to the liquid outlet 64 is largely prevented, there will be a slight drift ofthe liquid rearwardly within the shell.

Much of the liquid will, however, flow almost directly diametrically across the shell at all longitudinal regions thereof. This drift `is enhanced by the provision of the two holes 82 in the .end wall l76 of the manifold 70 and the absence of holes in the end wall 78. A

Due to the fact that the liquid issuing from the forwar .liquid `distribution holes 80 in the manifold 70 is colder j than the liquid issuing from the rear holes and, due to the h fact that the forward regions of the fire tubes 44 yare appreciablyhotter than the rear regions of these tubes, a comparatively large temperature differential obtains between theiliquid `phase and the gaseous phase of the boiler near the combustion chamber 14. In the rear region of the boiler where some of the heat within the `fire tube has been expended, the temperature differential is less but, due to the gradual or slight tendency for rear- .ward fiow of liquid inthe boiler shell, less heat is required to bring the temperature of the liquid to a prede-` termined maximum.' By such arrangement, substantially uniform heating takesvplace within the shell and maximum heat transfer eiciency is attained.` Still further, by reason of such uniform heating, thermal elongation of the `various fire tubes 44 will' tend to be equalized, no

one tube or group of tubes becomes appreciably longer than another tube or -group of tubes at any given instant and for any given period of heat increase or decrease, for example, during firing up of the combustion chamber. Any lateral displacement of either or both tube sheets 18 and 2.0 which may take place will be a more or less overall displacement and will result in gradual and uniform bulging of the tube sheets and well within the capabilities of the welds or other sealing means at the tube ends to withstand the displacement. Stated otherwise, no adjacent tube ends are likely to be displaced unequally in a direction transversely of the tube sheets in which they are anchored so that buckling of the tube sheet and mpture of the fire tubes is effectively prevented. Finally, due to the small size of the various holes 80 and the comparatively large number of said holes, as well as due to their wide longitudinal distribution along the distribution manifold 70, the provision of cold spots within the boiler shell is effectively eliminated. Thus, thermal shock which ordinarily results in sudden and undue tube distension or shrinking is prevented.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawing or described in this specification since the disclosure of the drawing, as previously stated, is more or less schematic albeit representative of principle of a typical installation. Matters of burner construction or burner selection, of combustion chamber design and many other factors associated with the boiler 10 may vary widely without disturbing the essential inventive features which reside largely in the distribution of thermal liquid throughout the boiler shell during boiler operation. Therefore, only insofar as the invention has been particularly pointed out in the accompanying claims is the same to be limited.

Having thus described the invention what we claim as new and desire to secure by Letters Patent is:

1. A fire tube boiler adapted for liquid phase heating and comprising an elongated horizontally disposed cylindrical boiler shell, means defining a combustion chamber at the front end of said boiler shell, means defining a flue gas collector at the rear end of the boiler shell, a front tube sheet separating the interior of the shell from the combustion chamber, a rear tube sheet separating the interior of the shell from the flue gas collector, a plurality of parallel horizontally disposed fire tubes extending between the two tube sheets, having their ends anchored therein, and establishing communication between the combustion chamber and the iiue gas collector, said shell being provided with an inlet opening for thermal liquid at the bottom of the shell, an elongated inverted troughlike distribution manifold disposed entirely within the cylindrical confines of the shell, arranged in sealing engagement with the inside surface of the shell, encompassing and in communictaion with the liquid inlet, and extending from a region adjacent to one of said tube sheets to a region adjacent to the other tube sheet and in a direction parallel to the longitudinal axis of the shell, said distribution manifold having a semi-cylindrical side wall and semi-circular front and rear end walls, said side wall being provided with two longitudinally extending rows of spaced liquid distribution holes therethrough, said rows being disposed on opposite sides of a diametric plane passing through the longitudinal central axis of the distribution manifold, said shell being provided `with an outlet opening for thermal liquid at the top of the shell.

2. A tire tube boiler as set forth in claim 1 and wherein said front end wall of the distribution manifold is provided with a liquid distribution hole therein opposing the front tube sheet.

3. A tire tube boiler as set forth in claim 1 and wherein said front end wall of the distribution manifold is provided with a pair of liquid distribution holes thereon opposing the front tube sheet, said latter holes being horizontally spaced from each other.

4. A fire tube boiler adapted for liquid phase heating and coniprising an elongated horizontally disposed cylindrical boiler shell, means defining a combustion chamber at the front end of said boiler shell, means defining a Hue gas Collector at the rear end of the boiler shell, a front tube sheet separating the interior of the shell from the combustion chamber, a rear tube sheet separating the interior of the shell from the flue gas collector, a plurality of parallel horizontally disposed re tubes extending between the two tube sheets, having their ends anchored therein, and establishing communication between the combustion chamber and the flue gas collector, said shell being provided with an inlet opening for thermal liquid at the bottom of the shell and with an outlet opening for such liquid at the top of the shell, an elongated inverted trough-like liquid distribution manifold disposed entirely within the cylindrical contines of the shell, arranged in sealing engagement with the inside surface of the shell, encompassing and in communication with the liquid inlet, and extending from a region adjacent to one of said tube sheets to a region adjacent to the other tube sheet and in a direction parallel to the longitudinal axis of the shell, said distribution manifold having a semi-cylindrical side wall and semi-circular front and rear end walls, said side wall being provided with two longitudinally extending rows of spaced liquid distribution holes therethrough, said rows being disposed on opposite sides of a diametric plane passing through the longitudinal central axis of the distribution manifold, and an elongated upright troughlike liquid collection manifold disposed] entirely within the cylindrical confines of the shell, arranged in sealing engagement with the inside surface of the shell, encomaes-1,529

passing and in communication with the liquid outlet, and extending from a region adjacent to one of said tube sheets to a region adjacent to the other tube sheet and in a direction parallel to the longitudinal axis of the shell, said collection manifold having a semi-cylindrical side wall and semi-cylindrical front and rear end walls, said side wall of the distribution manifold being provided with a row of longitudinally spaced liquid entrance holes therein.

5. A ire tube boiler as set forth in claim 4, wherein said side wall of the collection manifold is provided with a second row of longitudinally spaced liquid entrance holes and the two rows of liquid entrance holes are disposed on opposite sides of said diametric plane.

6. A fire tube boiler as set forth in claim 4 and wherein the inlet opening is disposed adjacent to said front tube sheet and the outlet opening is disposed adjacent to said rear tube sheet.

7. A re tube boiler as set forth in claim 4 and wherein the semi-circular front end wall of the liquid collection manifold is provided with a plurality of liquid entrance holes therein.

8. A tire tube boiler as set forth in claim 4 and wherein the semi-circular front end walls of the liquid distribution manifold and of the liquid collection manifold are provided with a plurality of liquid distribution and liquid entrance holes, respectively, therein.

9. A fire tube boiler adapted for liquid phase heating and comprising an elongated horizontally disposed cylindrical boiler shell, means defining a combustion chamber at the front end of said boiler shell, means defining a liuc gas collector at the rear end of the boiler shell, a front tube sheet separating the interior of the shell from the combustion chamber, a rear tube sheet separating the interior of the shell from the flue gas collector, a plurality of parallel horizontally disposed re tubes extending between the two tube sheets, having their ends anchored therein, and establishing communication between the combustion chamber and the tiue gas collector, said shell being provided with an inlet opening for thermal liquid at the bottom of the shell and with an outlet opening for thermal liquid at the top of the shell, an elongated inverted trough-like distribution manifold disposed entirely within the cylindrical contines of the shell, arranged in sealing engagement with the inside surface of the shell, encompassing and in communication with the liquid inlet and extending from a region adjacent to one of said tube sheets to a region adjacent to the other tube sheet and in a direction parallel to the longitudinal axis of the shell, said distribution manifold having a semi-cylindrical side wall and semi-circular front and rear end walls, said side wall being provided with two longitudinally extending rows of spaced liquid distribution holes therethrough, said rows being disposed on opposite sides of a diametric plane passing through the longitudinal central axis of the distribution manifold, and an upright troughlike liquid collection manifold disposed entirely within the confines of the shell, arranged in sealing engagement with the inside surface of the shell, encompassing and in communication with the liquid outlet, and extending from a region adjacent to one of said tube sheets to a region adjacent to the other tube sheet and in a direction parallel to the longitudinal axis of the shell, said collection manifold having a semi-cylindrical side wall and semi-cylindrical front and rear end walls, said side Wall of the collection manifold being provided with two longitudinally extending rows of spaced liquid entrance holes therein, said latter rows being disposed on opposite sides of a diametric plane passing through the longitudinal central axis of the collection manifold, the semi-circular front end walls of the liquid distribution manifold and of the liquid collection manifold being provided with a plurality of liquid distribution and liquid entrance holes, respectively, therein, the rear end walls of both the liquid distribution manifold and the liquid collection manifold being imperforate, said liquid inlet at the bottom of the shell being disposed adjacent to the front tube sheet and the liquid outlet at the top of the shell being disposed adjacent to the rear tube sheet.

References Cited by the Examiner UNITED STATES PATENTS 456,923 7/1891 Barnstead 165-160 543,688 7/1895 Keasbey 122-420 X 1,051,996 2/1913 Hammond 122-412 FOREIGN PATENTS 206,639 6/ 1956 Australia. 216,726 12/ 1909 Germany.

FREDERICK L. MATTESON, I R., Primary Examiner.

CHARLES J. MYHRE, Examiner. 

1. A FIRE TUBE BOILER ADAPTED FOR LIQUID PHASE HEATING AND COMPRISING AN ELONGATED HORIZONTALLY DISPOSED CYLINDRICAL BOILER SHELL, MEANS DEFINING A COMBUSTION CHAMBER AT THE FRONT END OF SAID BOILER SHELL, MEANS DEFINING A FLUE GAS COLLECTOR AT THE REAR END OF THE BOILER SHELL, A FRONT TUBE SHEET SEPARATING THE INTERIOR OF THE SHELL FROM THE COMBUSTION CHAMBER, A REAR TUBE SHEET SEPARATING THE INTERIOR OF THE SHELL FROM THE FLUE GAS COLLECTOR, A PLURALITY OF PARALLEL HORIZONTALLY DISPOSED FIRE TUBES EXTENDING BETWEEN THE TWO TUBE SHEETS, HAVING THEIR ENDS ANCHORED THEREIN, AND ESTABLISHING COMMUNICATION BETWEEN THE COMBUSTION CHAMBER AND THE FLUE GAS COLLECTOR, SAID SHELL BEING PROVIDED WITH AN INLET OPENING FOR THERMAL LIQUID AT THE BOTTOM OF THE SHELL, AN ELONGATED INVERTED TROUGHLIKE DISTRIBUTION MANIFOLD DISPOSED ENTIRELY WITHIN THE CYLINDRICAL CONFINES OF THE SHELL, ARRANGED IN SEALING ENGAGEMENT WITH THE INSIDE SURFACE OF THE SHELL, ENCOMPASSING AND IN COMMUNICATION WITH THE LIQUID INLET, AND EXTENDING FROM A REGION ADJACENT TO ONE OF SAID TUBE SHEETS TO A REGION ADJACENT TO THE OTHER TUBE SHEET AND IN A DIRECTION PARALLEL TO THE LONGITUDINAL AXIS OF THE SHELL, SAID DISTRIBUTION MANIFOLD HAVING A SEMI-CYLINDRICAL SIDE WALL AND SEMI-CIRCULAR FRONT AND REAR END WALLS, SAID SIDE WALL BEING PROVIDED WITH TWO LONGITUDINALLY EXTENDING ROWS OF SPACED LIQUID DISTRIBUTION HOLES THERETHROUGH, SAID ROWS BEING DISPOSED ON OPPOSITE SIDES OF A DIAMETRIC PLANE PASSING THROUGH THE LONGITUDINAL CENTRAL AXIS OF THE DISTRIBUTION MANIFOLD, SAID SHELL BEING PROVIDED WITH AN OUTLET OPENING FOR THERMAL LIQUID AT THE TOP OF THE SHELL. 